Performance-driven movement of applications between containers with different access protocols

ABSTRACT

An apparatus in one embodiment comprises at least one processing device. The at least one processing device is configured to monitor performance of respective ones of a plurality of paths for accessing a logical storage device, and responsive to detection of at least one specified condition in the monitored performance relating to at least a subset of the paths, to move at least one application from a first container that utilizes a first access protocol to access the logical storage device to a second container that utilizes a second access protocol different than the first access protocol to access the logical storage device. For example, in some embodiments, the at least one processing device is configured to move an application from first container that utilizes a SCSI access protocol to a second container that utilizes an NVMe access protocol, and vice versa, responsive to detected performance issues.

FIELD

The field relates generally to information processing systems, and moreparticularly to storage in information processing systems.

BACKGROUND

Storage arrays and other types of storage systems are often shared bymultiple host devices over a network. Applications running on the hostdevices each include one or more processes that perform the applicationfunctionality. The processes issue input-output (IO) operations directedto particular logical storage volumes or other logical storage devices,for delivery by the host devices over selected paths to storage ports ofthe storage system. Different ones of the host devices can run differentapplications with varying workloads and associated IO patterns. Suchhost devices also generate additional IO operations in performingvarious data services such as migration and replication. Various typesof storage access protocols can be used by host devices to access thelogical storage volumes or other logical storage devices of the storagesystem, including by way of example Small Computer System Interface(SCSI) access protocols and NVM Express (NVMe) access protocols.However, a given host device will typically be configured to utilizeonly one access protocol at a time to access a particular logicalstorage device, and reconfiguring such a host device to utilize adifferent access protocol to access that logical storage device can beproblematic in some situations. For example, even though a storagesystem may support multiple access protocols like SCSI and NVMe for itslogical storage devices, transforming host device access from SCSI toNVMe using conventional techniques can be problematic. A need thereforeexists for improved techniques that can avoid the drawbacks ofconventional approaches.

SUMMARY

Illustrative embodiments provide performance-driven movement ofapplications between containers with different access protocols. Forexample, one or more embodiments can alter the particular accessprotocol through which a given logical storage volume or other logicalstorage device is accessed by one or more host devices, illustrativelyfrom a particular SCSI access protocol, such as SCSI over Fibre Channel(SCSI-FC), to a particular NVMe access protocol, such as NVMe overFabrics (NVMeF), or vice versa, based on congestion, errors and/or otherdetected performance conditions impacting access to that logical storagedevice using one of the access protocols. It is to be appreciated that awide variety of other types of storage access protocols can be used inother embodiments.

These and other arrangements disclosed herein can switch host deviceaccess to one or more logical storage devices between multiple accessprotocols by advantageously leveraging containers that use differentaccess protocols, and dynamically moving applications between suchcontainers, so as to enhance application survivability and to otherwiseimprove IO processing performance.

Some embodiments disclosed herein utilize a multi-path layer of one ormore host devices in implementing performance-driven movement ofapplications between containers with different access protocols, in amanner that provides enhanced access to the logical storage device andtherefore improved overall system performance.

In one embodiment, an apparatus comprises at least one processing devicecomprising a processor and a memory coupled to the processor. The atleast one processing device is configured to monitor performance ofrespective ones of a plurality of paths for accessing a logical storagedevice, and responsive to detection of at least one specified conditionin the monitored performance relating to at least a subset of the paths,to move at least one application from a first container that utilizes afirst access protocol to access the logical storage device to a secondcontainer that utilizes a second access protocol different than thefirst access protocol to access the logical storage device.

For example, in some embodiments, the at least one processing device isconfigured to move an application from first container that utilizes aSCSI access protocol such as SCSI-FC to access one or more logicalstorage devices to a second container that utilizes an NVMe accessprotocol such as NVMeF to access the one or more logical storagedevices, and vice versa, responsive to congestion, errors or otherdetected performance conditions currently impacting one or more pathsassociated with a particular one of the access protocols.

The at least one processing device illustratively comprises at least aportion of at least one host device coupled to at least one storagearray or other type of storage system via at least one network.

The paths in some embodiments are associated with respectiveinitiator-target pairs, with each of a plurality of initiators of theinitiator-target pairs comprising a corresponding host bus adaptor (HBA)of the at least one host device and each of a plurality of targets ofthe initiator-target pairs comprising a corresponding port of thestorage system.

The at least one host device illustratively comprises a multi-pathlayer, with the multi-path layer comprising at least one multi-pathinput-output (MPIO) driver configured to control delivery of IOoperations from the at least one host device to the storage system overselected paths through the network.

In some embodiments, monitoring performance of respective ones of aplurality of paths for accessing a logical storage device comprisesmonitoring performance of a first set of paths associated with the firstaccess protocol, and monitoring performance of a second set of pathsassociated with the second access protocol.

For example, monitoring performance of at least one of the first andsecond sets of paths illustratively comprises sending designated accessprotocol commands over corresponding ones of the paths, measuringresponse time to the access protocol commands, and repeating the sendingand measuring in each of a plurality of monitoring intervals. A widevariety of other types of performance monitoring techniques can be usedin other embodiments. As another example, monitoring performance ofrespective ones of a plurality of paths for accessing a logical storagedevice illustratively comprises monitoring fabric performance impactnotifications received from one or more switch fabrics. Combinations ofthese and other performance monitoring techniques can be used.

In some embodiments, detecting at least one specified condition in themonitored performance relating to at least a subset of the pathscomprises comparing at least one performance measure of the first set ofpaths associated with the first access protocol to at least oneperformance measure of the second set of paths associated with thesecond access protocol, and detecting at least a threshold differentialbetween the performance measures of the first and second sets of paths.

Multiple performance measures may be used in determining whether or notat least a threshold differential exists between different pathsassociated with different access protocols. For example, different pathsassociated with different access protocols may have similar responsetime measures, but host queue length may exhibit more than a thresholddifferential between the different paths. In such arrangements,determining whether at least a threshold differential exists can includecomparing first performance measures for different paths associated withdifferent access protocols, and if the threshold differential is notdetected using the first performance measures, one or more additionalcomparisons may be sequentially implemented using respective additionalperformance measures, such as host queue length, storage array portcongestion, and many others.

In some embodiments, monitoring performance of the first and second setsof paths associated with the respective first and second accessprotocols is performed at least in part by a multi-path layer of atleast one host device.

Additionally or alternatively, monitoring performance of the first andsecond sets of paths associated with the respective first and secondaccess protocols is performed at least in part by at least one containerorchestrator of at least one host device.

Accordingly, in some embodiments, a multi-path layer and a containerorchestrator can collaborate in at least portions of the performancemonitoring. For example, a container orchestrator can be configured togenerate different performance measures than those generated by themulti-path layer.

In some embodiments, the multi-path layer of the at least one hostdevice presents the logical storage device to the first and secondcontainers as respective first and second distinct pseudo devices. In anarrangement of this type, an operating system of the at least one hostdevice sees the logical storage device as the first and second distinctpseudo devices, rather than as a single logical storage device.

The multi-path layer of the at least one host device illustrativelydirects IO operations received from the first container for the firstpseudo device to a first HBA associated with the first access protocoland directs IO operations received from the second container for thesecond pseudo device to a second HBA associated with the second accessprotocol.

In some embodiments, the multi-path layer of the at least one hostdevice, responsive to detection of the at least one specified condition,instructs a container orchestrator of the at least one host device tomove the at least one application from the first container that utilizesthe first access protocol to access the logical storage device to thesecond container that utilizes the second access protocol to access thelogical storage device.

The multi-path layer of the at least one host device in some embodimentscomprises one or more kernel-space components implemented in a kernelspace of the at least one host device and one or more user-spacecomponents implemented in a user space of the at least one host device.The one or more user-space components of the multi-path layerillustratively comprise a user agent configured to provide an interfacebetween at least a subset of the one or more kernel-space components ofthe multi-path layer and at least one user-space component of acontainer orchestrator of the at least one host device.

These and other illustrative embodiments include, without limitation,apparatus, systems, methods and computer program products comprisingprocessor-readable storage media.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an information processing system configuredwith functionality for performance-driven movement of applicationsbetween containers with different access protocols, utilizing amulti-path layer of a host device in an illustrative embodiment.

FIG. 2 is a flow diagram of a process for performance-driven movement ofapplications between containers with different access protocols,utilizing a multi-path layer of a host device in an illustrativeembodiment.

FIG. 3 is a block diagram showing multiple layers of a layered systemarchitecture that includes a multi-path layer with functionality forperformance-driven movement of applications between containers withdifferent access protocols in an illustrative embodiment.

FIG. 4 shows an example of per-path performance information maintainedby a multi-path layer of a host device for use in providingperformance-driven movement of applications between containers withdifferent access protocols in an illustrative embodiment.

DETAILED DESCRIPTION

Illustrative embodiments will be described herein with reference toexemplary information processing systems and associated computers,servers, storage devices and other processing devices. It is to beappreciated, however, that these and other embodiments are notrestricted to the particular illustrative system and deviceconfigurations shown. Accordingly, the term “information processingsystem” as used herein is intended to be broadly construed, so as toencompass, for example, processing systems comprising cloud computingand storage systems, as well as other types of processing systemscomprising various combinations of physical and virtual processingresources. An information processing system may therefore comprise, forexample, at least one data center or other cloud-based system thatincludes one or more clouds hosting multiple tenants that share cloudresources. Numerous different types of enterprise computing and storagesystems are also encompassed by the term “information processing system”as that term is broadly used herein.

FIG. 1 shows an information processing system 100 configured inaccordance with an illustrative embodiment. The information processingsystem 100 comprises at least first and second host devices 102-1 and102-2, collectively referred to herein as host devices 102. The hostdevices 102 are coupled to a network 104 that comprises one or moreswitch fabrics. The host devices 102 communicate over the network 104via the one or more switch fabrics with at least first and secondstorage arrays 105-1 and 105-2, collectively referred to herein asstorage arrays 105. For example, the network 104 illustrativelycomprises at least one storage area network (SAN) and the one or moreswitch fabrics illustratively comprise respective distinct switchfabrics of a set of multiple switch fabrics interconnecting the hostdevices 102 with the storage arrays 105 over the one or more SANs. Eachof the one or more switch fabrics in some embodiments is associated witha different SAN.

The system 100 may be configured such that the first host device 102-1communicates with the first storage array 105-1 over a first switchfabric and communicates with the second storage array 105-2 over asecond switch fabric. Similarly, the second host device 102-2 cancommunicate with the first storage array 105-1 over the first switchfabric and communicate with the second storage array 105-2 over thesecond switch fabric. Numerous other interconnection arrangements arepossible.

Also, other types of networks can be used in other embodiments, andreferences to SANs, switch fabrics or other particular networkarrangements herein are for purposes of illustration only, asnon-limiting examples.

Although only two host devices 102 and two storage arrays 105 are shownin the figure, this is by way of illustrative example only, and otherembodiments can include additional instances of such elements. It isalso possible that alternative embodiments may include only a singlehost device.

The host devices 102 illustratively comprise respective computers,servers or other types of processing devices configured to communicatewith the storage arrays 105 over the network 104. For example, at leasta subset of the host devices 102 may be implemented as respectivevirtual machines of a compute services platform or other type ofprocessing platform. The host devices 102 in such an arrangementillustratively provide compute services such as execution of one or moreapplications on behalf of each of one or more users associated withrespective ones of the host devices 102. The term “user” herein isintended to be broadly construed so as to encompass numerousarrangements of human, hardware, software or firmware entities, as wellas combinations of such entities.

Compute and/or storage services may be provided for users under aPlatform-as-a-Service (PaaS) model, an Infrastructure-as-a-Service(IaaS) model and/or a Function-as-a-Service (FaaS) model, although it isto be appreciated that numerous other cloud infrastructure arrangementscould be used. Also, illustrative embodiments can be implemented outsideof the cloud infrastructure context, as in the case of a stand-alonecomputing and storage system implemented within a given enterprise.

The network 104 may be implemented using multiple networks of differenttypes to interconnect the various components of the informationprocessing system 100. For example, the network 104 may comprise aportion of a global computer network such as the Internet, althoughother types of networks can be part of the network 104, including a widearea network (WAN), a local area network (LAN), a satellite network, atelephone or cable network, a cellular network, a wireless network suchas a WiFi or WiMAX network, or various portions or combinations of theseand other types of networks. The network 104 in some embodimentstherefore comprises combinations of multiple different types of networkseach comprising processing devices configured to communicate usingInternet Protocol (IP) and/or other types of communication protocols.

As a more particular example, some embodiments may utilize one or morehigh-speed local networks in which associated processing devicescommunicate with one another utilizing Peripheral Component Interconnectexpress (PCIe) cards of those devices, and networking protocols such asInfiniBand, Gigabit Ethernet or Fibre Channel. Numerous alternativenetworking arrangements are possible in a given embodiment, as will beappreciated by those skilled in the art.

Although illustratively shown as separate from the network 104 in thefigure, at least portions of the storage arrays 105 may be consideredpart of the network 104 in some embodiments. For example, in embodimentsin which the network 104 comprises at least one SAN, the storage arrays105 may be viewed as part of the one or more SANs.

The storage arrays 105-1 and 105-2 comprise respective sets of storagedevices 106-1 and 106-2, collectively referred to herein as storagedevices 106, coupled to respective storage controllers 108-1 and 108-2,collectively referred to herein as storage controllers 108.

The storage devices 106 of the storage arrays 105 illustrativelycomprise solid state drives (SSDs). Such SSDs in some embodiments areimplemented using non-volatile memory (NVM) devices such as flashmemory. Other types of NVM devices that can be used to implement atleast a portion of the storage devices 106 include non-volatile randomaccess memory (NVRAM), phase-change RAM (PC-RAM), magnetic RAM (MRAM),resistive RAM, spin torque transfer magneto-resistive RAM (STT-MRAM),and Intel Optane™ devices based on 3D XPoint™ memory. These and variouscombinations of multiple different types of storage devices may also beused. For example, hard disk drives (HDDs) can be used in combinationwith or in place of SSDs or other types of NVM devices.

A given storage system as the term is broadly used herein can thereforeinclude a combination of different types of storage devices, as in thecase of a multi-tier storage system comprising, for example, amemory-based fast tier and a disk-based capacity tier. In such anembodiment, each of the fast tier and the capacity tier of themulti-tier storage system comprises a plurality of storage devices withdifferent types of storage devices being used in different ones of thestorage tiers. For example, the fast tier may comprise flash drives, NVMdrives or other types of SSDs while the capacity tier comprises HDDs.The particular storage devices used in a given storage tier may bevaried in other embodiments, and multiple distinct storage device typesmay be used within a single storage tier. The term “storage device” asused herein is intended to be broadly construed, so as to encompass, forexample, SSDs, HDDs, flash drives, NVM drives, hybrid drives or othertypes of storage devices.

In some embodiments, at least one of the storage arrays 105illustratively comprises one or more Unity™ or PowerMax™ storage arrays,commercially available from Dell Technologies. As another example, oneor both of the storage arrays 105 may comprise respective clusteredstorage systems, each including a plurality of storage nodesinterconnected by one or more networks. An example of a clusteredstorage system of this type is an XtremIO™ storage array from DellTechnologies, illustratively implemented in the form of a scale-outall-flash content addressable storage array.

A given storage system as the term is broadly used herein canadditionally or alternatively comprise, for example, network-attachedstorage (NAS), direct-attached storage (DAS) and distributed DAS.

Other additional or alternative types of storage products that can beused in implementing a given storage system in illustrative embodimentsinclude software-defined storage, cloud storage, object-based storageand scale-out storage. Combinations of multiple ones of these and otherstorage types can also be used in implementing a given storage system inan illustrative embodiment.

As mentioned above, communications between the host devices 102 and thestorage arrays 105 within the system 100 may utilize PCIe connections orother types of connections implemented over one or more networks such asnetwork 104. For example, illustrative embodiments can use interfacessuch as Internet SCSI (iSCSI), Serial Attached SCSI (SAS) and Serial ATA(SATA). Numerous other interfaces and associated communication protocolscan be used in other embodiments.

The storage arrays 105 in some embodiments may be implemented as part ofcloud infrastructure in the form of a cloud-based system such as anAmazon Web Services (AWS) system. Other examples of cloud-based systemsthat can be used to provide at least portions of the storage arrays 105and possibly other portions of system 100 include Google Cloud Platform(GCP) and Microsoft Azure.

As is apparent from the foregoing, terms such as “storage array” and“storage system” as used herein are intended to be broadly construed,and a given such storage array or storage system may encompass, forexample, multiple distinct instances of a commercially-available storagearray.

The storage devices 106 of the storage arrays 105 are configured tostore data utilized by one or more applications running on one or moreof the host devices 102. The storage devices 106 on one of the storagearrays 105 are illustratively arranged in one or more storage pools. Thestorage arrays 105 and their corresponding storage devices 106 areexamples of what are more generally referred to herein as “storagesystems.” A given such storage system in the present embodiment may beshared by the host devices 102, and in such arrangements may be referredto as a “shared storage system.”

The storage devices 106 of the storage arrays 105 implement logicalunits (LUNs) configured to store objects for users associated with thehost devices 102. These objects can comprise files, blocks or othertypes of objects. The host devices 102 interact with the storage arrays105 utilizing read and write commands as well as other types of commandsthat are transmitted over the network 104.

Such commands in some embodiments more particularly comprise SCSIcommands, although other types of commands may be used in otherembodiments, including commands that are part of a standard command set,or custom commands such as a “vendor unique command” or VU command thatis not part of a standard command set.

A given IO operation as that term is broadly used herein illustrativelycomprises one or more such commands. References herein to terms such as“input-output” and “IO” should be understood to refer to input and/oroutput. Thus, an IO operation relates to at least one of input andoutput. For example, an IO operation can comprise at least one read IOoperation and/or at least one write IO operation. More particularly, IOoperations may comprise write requests and/or read requests directed tostored data of a given one of the storage arrays 105.

Each IO operation is assumed to comprise one or more commands forinstructing at least one of the storage arrays 105 to perform particulartypes of storage-related functions such as reading data from or writingdata to particular logical storage volumes or other logical storagedevices of one or more of the storage arrays 105. Such commands areassumed to have various payload sizes associated therewith, and thepayload associated with a given command is referred to herein as its“command payload.”

A command directed by one of the host devices 102 to one of the storagearrays 105 is considered an “outstanding” command until such time as itsexecution is completed in the viewpoint of the sending host device, atwhich time it is considered a “completed” command. The commandsillustratively comprise respective SCSI commands, although other commandformats can be used in other embodiments. A given such command isillustratively defined by a corresponding command descriptor block (CDB)or similar format construct. The given command can have multiple blocksof payload associated therewith, such as a particular number of 512-byteSCSI blocks or other types of blocks.

Also, the term “storage device” as broadly used herein can encompass,for example, a logical storage device such as a LUN or other logicalstorage volume. A logical storage device can be defined in the storagearrays 105 to include different portions of one or more physical storagedevices. The storage devices 106 may therefore be viewed as comprisingrespective LUNs or other logical storage volumes. Logical storagedevices are also referred to herein as simply “logical devices.”

Each of the host devices 102 illustratively has multiple paths to eachof the storage arrays 105 via the network 104, with at least one of thestorage devices 106 of one of the storage arrays 105 being visible tothat host device on a given one of the paths, although numerous otherarrangements are possible. A given one of the storage devices 106 may beaccessible to a given host device over multiple paths. Different ones ofthe host devices 102 can have different numbers and types of paths tothe storage arrays 105.

Different ones of the storage devices 106 of the storage arrays 105illustratively exhibit different latencies in processing of IOoperations. In some cases, the same storage device may exhibit differentlatencies for different ones of multiple paths over which that storagedevice can be accessed from a given one of the host devices 102.

The host devices 102, network 104 and storage arrays 105 in the FIG. 1embodiment are assumed to be implemented using at least one processingplatform each comprising one or more processing devices each having aprocessor coupled to a memory. Such processing devices canillustratively include particular arrangements of compute, storage andnetwork resources. For example, processing devices in some embodimentsare implemented at least in part utilizing virtual resources such asvirtual machines (VMs) or Linux containers (LXCs), or combinations ofboth as in an arrangement in which Docker containers or other types ofLXCs are configured to run on VMs.

As another example, the host devices 102 in some embodimentsillustratively comprise an ESXi environment or other type of hostenvironment that supports non-disruptive movement of applicationsbetween ESXi servers or other types of servers, possibly using vMotionor other similar techniques to move VMs, in which those applicationexecute, from one server to another server.

Accordingly, in some embodiments, the host devices 102 are configured tosupport such application movement between those host devices. Thisapplication movement can be used as part of an automated seamlessmigration of a logical storage device between access protocols, althoughother types of automated seamless migration not involving applicationmovement can be used in other embodiments.

Additional examples of processing platforms utilized to implementstorage systems and possibly one or more associated host devices inillustrative embodiments will be described in more detail below.

The host devices 102 and the storage arrays 105 may be implemented onrespective distinct processing platforms, although numerous otherarrangements are possible. For example, in some embodiments at leastportions of the host devices 102 and the storage arrays 105 areimplemented on the same processing platform. The storage arrays 105 cantherefore be implemented at least in part within at least one processingplatform that implements at least a subset of the host devices 102.

The term “processing platform” as used herein is intended to be broadlyconstrued so as to encompass, by way of illustration and withoutlimitation, multiple sets of processing devices and associated storagesystems that are configured to communicate over one or more networks.For example, distributed implementations of the host devices 102 arepossible, in which certain ones of the host devices 102 reside in onedata center in a first geographic location while other ones of the hostdevices 102 reside in one or more other data centers in one or moreother geographic locations that are potentially remote from the firstgeographic location. Thus, it is possible in some implementations of thesystem 100 for different ones of the host devices 102 to reside indifferent data centers than the storage arrays 105. The storage arrays105 can be similarly distributed across multiple data centers.

Although in some embodiments certain commands used by the host devices102 to communicate with the storage arrays 105 illustratively compriseSCSI commands, other types of commands and command formats can be usedin other embodiments. For example, some embodiments can implement IOoperations utilizing command features and functionality associated withNVM Express (NVMe), as described in the NVMe Specification, Revision1.3, May 2017, which is incorporated by reference herein. Other storageprotocols of this type that may be utilized in illustrative embodimentsdisclosed herein include NVMe over Fabrics, also referred to as NVMeF,and NVMe over Transmission Control Protocol (TCP), also referred to asNVMe/TCP.

The storage arrays 105-1 and 105-2 in some embodiments may be arrangedin an active-active configuration, although use of such a configurationis not required. In an example of an active-active configuration thatmay be used, data stored in one of the storage arrays 105 is replicatedto the other one of the storage arrays 105 utilizing a replicationprocess. Such data replication across the multiple storage arrays 105can be used to facilitate failure recovery in the system 100. One of thestorage arrays 105 may therefore operate as a production storage arrayrelative to the other storage array which operates as a backup orrecovery storage array. Examples of active-active configurations include“metro” or “stretched” high availability storage array configurations.The term “active-active configuration” as used herein is thereforeintended to be broadly construed.

The storage arrays 105-1 and 105-2 may be configured to participate in areplication process, such as a synchronous replication process. Inaccordance with one type of synchronous replication process, a given oneof the host devices 102 writes data to one of the storage arrays 105,and that host device receives an acknowledgement of success only afterthe data has been successfully written to both of the storage arrays105. For example, if the host device directs a write to the firststorage array 105-1, that storage array mirrors the write to the secondstorage array 105-2 and receives an acknowledgement of success back fromthe second storage array 105-2. The first storage array 105-1 thenresponds back to the host device with an acknowledgement of success.

This type of synchronous replication process is therefore configured tomirror data writes from one or more of the host devices 102 to both ofthe storage arrays 105. Other types of replication processes may be usedin other embodiments.

For example, a “replication process” as that term is broadly used hereinmay include both asynchronous and synchronous replication modes as wellas support for concurrent operation of such modes and separate operationof the individual modes. It is also possible in some embodiments that agiven replication process implemented using storage arrays 105 maycomprise only synchronous replication or only asynchronous replication,instead of multiple distinct replication modes.

It is assumed that the storage controllers 108 of the respective storagearrays 105 each comprise replication control logic and a snapshotgenerator. The replication control logic controls performance of theabove-noted replication process. The snapshot generator can be used, forexample, to generate snapshots of one or more storage volumes that aresubject to synchronous replication in conjunction with active-activestorage clustering, and in a wide variety of different migrationscenarios.

The snapshots generated by the storage controllers 108 of the storagearrays 105 illustratively comprise respective point-in-time (PIT)replicas of the storage volumes. Multiple snapshots generated over timefor a given storage volume can collectively comprise a “snapshot group”and information characterizing those snapshots in some embodiments isstored in the form of a snapshot tree or other arrangement of one ormore data structures suitable for storing information characterizing asnapshot group. In some embodiments, a snapshot tree for a storagevolume is configured to add a new node each time a new snapshot isgenerated for that storage volume. The term “snapshot” as used herein isintended to be broadly construed, and in some embodiments may encompassa complete PIT replica or other types of information characterizing thestate of a given storage volume at a particular time.

A given storage volume implemented on one or both of the storage arrays105 in the system 100 illustratively comprises a set of one or more LUNsor other storage volumes of one or both of the storage arrays 105. Eachsuch LUN or other storage volume is assumed to comprise at least aportion of a physical storage space of one or more of the storagedevices 106 of the corresponding storage arrays 105.

The host devices 102 comprise respective sets of containers 109-1 and109-2, collectively referred to as containers 109. For example, suchcontainers can comprise Docker containers or other types of LXCsillustratively implemented using respective operating system kernelcontrol groups of their corresponding host devices 102. The containersin some embodiments may run on virtual machines, and therefore may beused in combination with other virtualization infrastructure such as VMsimplemented using a hypervisor, although numerous other arrangements arepossible. Each of the containers 109 may be utilized to execute one ormore different applications within the system 100.

Although not explicitly shown in the figure, it is assumed that each ofthe host devices 102 comprises at least one container orchestrator, suchas a Docker orchestrator, that manages various aspects of the operationof the containers 109 implemented on that host device. In someembodiments herein, one or more such container orchestrators are eachconfigured to interact with one or more components of a multi-path layerof the host devices 102. Each host device can include multiple containerorchestrators for different groups of containers. Alternatively, one ormore container orchestrators can be shared by the host devices 102. Theterm “container orchestrator” as used herein is therefore intended to bebroadly construed to encompass an entity that manages Docker containersor other types of LXCs that are implemented using operating system levelvirtualization on one or more host devices

The host devices 102 further comprise respective sets of IO queues 110-1and 110-2, and respective MPIO drivers 112-1 and 112-2. The MPIO drivers112 collectively comprise a multi-path layer of the host devices 102.The multi-path layer provides automated path selection functionalityusing respective instances of path selection logic 114-1 and 114-2implemented within the MPIO drivers 112.

In some embodiments, the multi-path layer additionally supports what isreferred to herein as “performance-driven application movement” betweencontainers for altering access protocols used by applications executingon the host devices 102 to access logical storage devices of the storagearrays 105. Such functionality for performance-driven movement ofapplications between containers with different access protocols may beimplemented, for example, at least in part in the multi-path layer, andmay additionally or alternatively be implemented at least in part in oneor more other system components, such as one or more containerorchestrators of at least one of the host devices 102 and/or respectivemigration control logic instances of at least one of the host devices102.

The MPIO drivers 112 may comprise, for example, otherwise conventionalMPIO drivers, such as PowerPath® drivers from Dell Technologies,suitably modified in the manner disclosed herein to supportperformance-driven application movement. Other types of MPIO driversfrom other driver vendors may be suitably modified to incorporatefunctionality for performance-driven application movement as disclosedherein.

The MPIO driver 112-1 is configured to select IO operations from itscorresponding set of IO queues 110-1 for delivery to the storage arrays105 over the network 104. The sources of the IO operations stored in theset of IO queues 110-1 illustratively include respective processes ofone or more applications executing on the host device 102-1. Other typesof sources of IO operations may be present in a given implementation ofsystem 100.

The paths over which the IO operations are sent from the host device102-1 to the storage arrays 105 illustratively comprise paths associatedwith respective initiator-target pairs, with each initiator comprising ahost bus adaptor (HBA) or other initiating entity of the host device102-1 and each target comprising a storage array port or other targetedentity corresponding to one or more of the storage devices 106 of thestorage arrays 105. As noted above, the storage devices 106 of thestorage arrays 105 illustratively comprise LUNs or other types oflogical storage devices.

For example, in selecting particular ones of the paths for delivery ofthe IO operations to the storage arrays 105, the path selection logic114-1 of the MPIO driver 112-1 illustratively implements a pathselection algorithm that selects particular ones of the paths at leastin part as a function of path information such as host device HBA andstorage array port, with the path selection algorithm being configuredto balance the IO operations over the paths or to achieve other loadbalancing or performance goals.

Selecting a particular one of multiple available paths for delivery of aselected one of the IO operations of the set of IO queues 110-1 is moregenerally referred to herein as “path selection.” Path selection as thatterm is broadly used herein can in some cases involve both selection ofa particular IO operation and selection of one of multiple possiblepaths for accessing a corresponding logical device of one of the storagearrays 105. The corresponding logical device illustratively comprises aLUN or other logical storage volume to which the particular IO operationis directed.

A given retry of a failed IO operation under such a path selectionalgorithm can select a path having a different host device HBA andstorage array port for a given retry than that of the path selected forthe original failed IO operation.

The paths between the host devices 102 and the storage arrays 105 canchange over time. For example, the addition of one or more new pathsfrom host device 102-1 to the storage arrays 105 or the deletion of oneor more existing paths from the host device 102-1 to the storage arrays105 may result from respective addition or deletion of at least aportion of the storage devices 106 of the storage arrays 105. Additionor deletion of paths can also occur as a result of zoning and maskingchanges or other types of storage system reconfigurations performed by astorage administrator or other user.

In some embodiments, paths are added or deleted in conjunction withaddition of a new storage array or deletion of an existing storage arrayfrom a storage system that includes multiple storage arrays, possibly inconjunction with configuration of the storage system for at least one ofa migration operation and a replication operation.

In these and other situations, path discovery scans may be repeated asneeded in order to discover the addition of new paths or the deletion ofexisting paths.

A given path discovery scan can be performed utilizing knownfunctionality of conventional MPIO drivers, such as PowerPath® drivers.

The path discovery scan in some embodiments may be further configured toidentify one or more new LUNs or other logical storage volumesassociated with the one or more new paths identified in the pathdiscovery scan. The path discovery scan may comprise, for example, oneor more bus scans which are configured to discover the appearance of anynew LUNs that have been added to the storage arrays 105 as well todiscover the disappearance of any existing LUNs that have been deletedfrom the storage arrays 105.

The MPIO driver 112-1 in some embodiments comprises a user-space portionand a kernel-space portion. The kernel-space portion of the MPIO driver112-1 may be configured to detect one or more path changes of the typementioned above, and to instruct the user-space portion of the MPIOdriver 112-1 to run a path discovery scan responsive to the detectedpath changes. Other divisions of functionality between the user-spaceportion and the kernel-space portion of the MPIO driver 112-1 arepossible.

For each of one or more new paths identified in the path discovery scan,the host device 102-1 may be configured to execute a host registrationoperation for that path. The host registration operation for a given newpath illustratively provides notification to the corresponding one ofthe storage arrays 105 that the host device 102-1 has discovered the newpath.

As is apparent from the foregoing, MPIO driver 112-1 of host device102-1 is configured to control delivery of IO operations from the hostdevice 102-1 to the first and second storage arrays 105 over selectedpaths through the network 104.

The MPIO driver 112-1 is also configured to implement at least portionsof functionality for performance-driven movement of applications betweencontainers with different access protocols, such as between first andsecond different containers of host device 102-1. Other host devicecomponents, such as container orchestrators and/or migration controllogic implemented in one or more host device processors, canadditionally or alternatively implement aspects of the functionality forperformance-driven movement of applications between containers withdifferent access protocols in host device 102-1. The disclosedembodiments are therefore not limited to embodiments in whichfunctionality for performance-driven movement of applications iscontrolled at least in part by an MPIO driver or multi-path layer.

As indicated previously, migration of logical storage volumes or otherlogical storage devices across multiple access protocols can beproblematic. For example, host-based seamless migration in these andother contexts can be inefficient, consuming significant amounts ofcomputational and network resources of the host device. Suchrequirements of conventional approaches can negatively impact theseamless migration process and thereby degrade overall systemperformance.

For example, some conventional host-based migration processes such asPowerPath® Migration Enabler (PPME) typically require that a hostadministrator and a storage administrator cooperate in setting up andexecuting the migration process, which in some circumstances cancomplicate the migration effort.

Storage-based migration processes such as Non-Destructive Migration(NDM) of a source device to a target device do not require suchcooperation, but typically require device spoofing. More particularly,these storage-based migration processes typically require the targetdevice to spoof the source device identifier or ID. This spoofing posesproblems since the target device ID on the target array in some casesdoes not reflect the actual storage array on which the device resides.For example, if the storage array information is embedded in the deviceID, and the target device is spoofing the source device by using thesource device ID, the storage array information embedded in the spoofeddevice ID will indicate the source array and not the target array, eventhough the target device is located on the target array.

Host-based migration processes such as the above-noted PPME allow thetarget device to keep its own device ID, as an MPIO driver of amulti-path layer can merge the two device IDs into a single device IDfor presentation to a host device processor layer, thereby avoiding theproblems associated with spoofing.

The performance-driven application movement techniques of illustrativeembodiments disclosed herein provide significant advantages over theseand other conventional approaches.

For example, some embodiments are configured to facilitate migration ofa logical storage device from use of a first access protocol such asSCSI-FC to use of second access protocol such as NVMeF, and vice versa,responsive to detected performance conditions currently impacting one ofthe access protocols, in a particularly efficient manner thatintelligently leverages multi-pathing functionality of a given hostdevice environment. Such performance-driven application movement can beimplemented across two or more distinct access protocols of numerousother types in other embodiments.

In some embodiments, the migration is illustratively implemented using aprocess in which one or more hosts previously accessing a logicalstorage device via a particular one of the access protocols arereconfigured to access the logical storage device via the other one ofthe access protocols. In some arrangements of this type, it is assumedthat the host OS is unable to access the logical storage device usingthe first and second access protocols simultaneously, and can insteadonly access the logical storage device using one of the access protocolsat any given time. Accordingly, some embodiments herein configure anMPIO layer to determine, for example, that one or more paths associatedwith one of the access protocols are currently performing significantlybetter than one or more other paths associated with the other one of theaccess protocols, and responsive to such a determination, to move atleast one application from a first container that utilizes a firstaccess protocol to access the logical storage device to a secondcontainer that utilizes a second access protocol different than thefirst access protocol to access the logical storage device. Suchembodiments leverage the MPIO layer to provide performance-drivenmigration of applications between utilization of different accessprotocols for one or more logical storage devices.

In accordance with the functionality for performance-driven movement ofapplications of illustrative embodiments, an MPIO layer comprising oneor more of the MPIO drivers 112-1 and 112-2 of the respective hostdevices 102-1 and 102-2 is configured to monitor performance ofrespective ones of a plurality of paths for accessing at least onelogical storage device, and responsive to detection of at least onespecified condition in the monitored performance relating to at least asubset of the paths, to move at least one application from a firstcontainer that utilizes a first access protocol to access the logicalstorage device to a second container that utilizes a second accessprotocol different than the first access protocol to access the logicalstorage device. The application movement in some embodiments isperformed at least in part by at least one container orchestrator,responsive to an application movement instruction received from the MPIOlayer, although numerous other arrangements are possible.

The application movement is illustratively from one container on aparticular one of the host devices 102 to another container on that samehost device, although it is possible in some embodiments for theapplication movement to be from a container on one of the host devices102 to a container on another one of the host devices 102. Terms such as“moving an application” between containers as used herein are intendedto be broadly construed, so as to encompass such arrangements.

The above-noted MPIO layer illustratively runs on at least oneprocessing device that comprises at least a portion of at least one ofthe host devices 102 coupled to the storage arrays 105 via the network104. Other arrangements of one or more processing devices, eachcomprising at least one processor and at least one memory coupled to theat least one processor, may be used in other embodiments. The at leastone container orchestrator illustratively runs on the same at least oneprocessing device that the MPIO layer runs on. For example, differentcontainer orchestrators can be implemented on different ones of the hostdevices 102.

As indicated previously, the first and second access protocolsillustratively comprise respective SCSI and NVMe access protocols, suchas SCSI-FC and NVMeF access protocols, although other arrangements oftwo or more distinct access protocols can be used in other embodiments.

In some embodiments, the paths are associated with respectiveinitiator-target pairs, with each of a plurality of initiators of theinitiator-target pairs comprising an HBA of one of the host devices 102and each of a plurality of targets of the initiator-target pairscomprising a corresponding port of one of the storage arrays 105.

In some embodiments, monitoring performance of respective ones of aplurality of paths for accessing a logical storage device comprisesmonitoring performance of a first set of paths associated with the firstaccess protocol, and monitoring performance of a second set of pathsassociated with the second access protocol.

As a more particular example, monitoring performance of at least one ofthe first and second sets of paths comprises sending designated accessprotocol commands over corresponding ones of the paths, measuringresponse time to the access protocol commands, and repeating the sendingand measuring in each of a plurality of monitoring intervals. Numerousother performance monitoring techniques generating other types ofmetrics or other performance measures can be used in other embodiments.The response times are examples of what are also referred to herein as“latencies” of the respective paths. Again, response times or othertypes of measured latencies are examples of what are more generallyreferred to herein as “performance measures” generated as part of theperformance monitoring.

In some embodiments, monitoring performance of respective ones of theplurality of paths for accessing the logical storage device comprisesmonitoring fabric performance impact notifications (FPINs) received fromone or more switch fabrics 104. Performance conditions impacting one ormore paths as indicated by such FPINs can be used to control swapping orother types of switching of the logical storage device between accessprotocols, by moving applications between containers as disclosedherein.

Detecting at least one specified condition in the monitored performancerelating to at least a subset of the paths illustratively comprisescomparing at least one performance measure of the first set of pathsassociated with the first access protocol to at least one performancemeasure of the second set of paths associated with the second accessprotocol, and detecting at least a threshold differential between theperformance measures of the first and second sets of paths. For example,in the presence of at least a threshold differential, such as at least athreshold percentage difference between performance measures for therespective path sets, one of the first and second access protocolsillustratively has a relatively high level of performance, compared tothe other one of the first and second access protocols, which has arelatively low level of performance. Illustrative embodiments hereindynamically switch at least one logical storage device from the accessprotocol currently having the relatively low level of performance to theaccess protocol currently having the relatively high level ofperformance, by moving at least one application that utilizes thatlogical storage device between containers.

The response time measurements in some embodiments utilize VU commandsthat primarily measure SAN performance. Measurements of this type aregenerally not impacted by storage array port load, but instead reflectswitch delays in the SAN. Once again, this is only an example, andnumerous other types of performance measures can be used in comparingperformance of paths associated with one access protocol to performanceof paths associated with another access protocol.

Multiple performance measures may be used in determining whether or notat least a threshold differential exists between paths associated withthe first and second protocols. For example, different paths associatedwith different access protocols may have similar response time measures,but host queue length may exhibit more than a threshold differentialbetween the different paths. In such arrangements, determining whetherat least a threshold differential exists can include comparing firstperformance measures for different paths associated with differentaccess protocols, and if the threshold differential is not detectedusing the first performance measures, one or more additional comparisonsmay be sequentially implemented using respective additional performancemeasures, such as host queue length, storage array port congestion, andmany others.

For example, in some embodiments, comparing performance for differentpaths associated with different access protocols is not based solely onresponse time, but instead response time is one of multiple performancemeasures that are used in the comparison. If response time for thedifferent paths associated with the different protocols is substantiallythe same, the comparison may then move to host queue length, and thiscontinues until either a threshold differential is detected or allcomparisons are complete.

As indicated above, in some embodiments, monitoring performance of thefirst and second sets of paths associated with the respective first andsecond access protocols is performed at least in part by the MPIO layerof at least one of the host devices 102.

Additionally or alternatively, monitoring performance of the first andsecond sets of paths associated with the respective first and secondaccess protocols is performed at least in part by at least one containerorchestrator of at least one of the host devices 102.

Accordingly, in some embodiments, the MPIO layer and at least onecontainer orchestrator of one or more of the host devices 102 cancollaborate in at least portions of the performance monitoring. Forexample, one or more container orchestrators can be configured togenerate different performance measures than those generated by the MPIOlayer. A detected performance condition can therefore relate to one ormore performance measures generated by the MPIO layer and one or moreadditional performance measures generated by at least one containerorchestrator, possibly implemented on the same one or more host devices102.

Terms such as “monitoring performance” as used herein are thereforeintended to be broadly construed, so as to encompass, for example,generation of performance-related metrics or other measurements by anMPIO layer, by a container orchestrator, and/or by collaborativeinteraction of an MPIO layer and a container orchestrator. Monitoringperformance in some embodiments may therefore be performed only by acontainer orchestrator, although numerous other arrangements arepossible.

In some embodiments, the MPIO layer of at least one of the host devices102 presents the logical storage device to the first and secondcontainers as respective first and second distinct pseudo devices. In anarrangement of this type, an operating system of at least one of thehost devices 102 sees the logical storage device as the first and seconddistinct pseudo devices, rather than as a single logical storage device.Such a pair of pseudo devices, as the term “pseudo device” is broadlyused herein, have different device IDs, illustratively assigned inaccordance with the different first and second access protocols, but theMPIO layer manages them as a single logical storage device of at leastone of the storage arrays 105.

The MPIO layer of at least one of the host devices 102 illustrativelydirects IO operations received from the first container for the firstpseudo device to a first HBA associated with the first access protocoland directs IO operations received from the second container for thesecond pseudo device to a second HBA associated with the second accessprotocol.

In some embodiments, the MPIO layer of at least one of the host devices102, responsive to detection of the at least one specified condition,instructs a container orchestrator of at least one of the host devices102 to move the at least one application from the first container thatutilizes the first access protocol to access the logical storage deviceto the second container that utilizes the second access protocol toaccess the logical storage device.

The MPIO layer of at least one of the host devices 102 in someembodiments comprises one or more kernel-space components implemented ina kernel space of at least one of the host devices 102 and one or moreuser-space components implemented in a user space of at least one of thehost devices 102. The one or more user-space components of the MPIOlayer illustratively comprise a user agent configured to provide aninterface between at least a subset of the one or more kernel-spacecomponents of the MPIO layer and at least one user-space component of acontainer orchestrator of at least one of the host devices 102.

In illustrative embodiments, as the monitored performance changes overtime, different access protocols are utilized to access the logicalstorage device at different times, based at least in part on themonitored performance, which drives movement of at least onecorresponding application between different containers associated withdifferent ones of the access protocols.

Accordingly, at least one of the MPIO drivers 112 of at least one of thehost devices 102 is configured to dynamically move an applicationbetween different containers using different access protocols, so as toeffectively switch the logical storage device between utilization of thefirst and second access protocols over a plurality of access protocolswitching instances, responsive to detection of respective specifiedconditions in the monitored performance of paths associated with one ofthe access protocols relative to the monitored performance of pathsassociated with the other one of the access protocols.

Additionally or alternatively, at least one of the MPIO drivers 112 ofat least one of the host devices 102 is configured to monitor theperformance of the paths over a plurality of monitoring intervals andfor each of one or more of the monitoring intervals to select aparticular one of the first and second access protocols for utilizationby the logical storage device in that monitoring interval based at leastin part on the monitored performance of the paths for at least oneprevious one of the monitoring intervals, and to instruct the movementof at least one application from its current container that does not usethe selected access protocol to access the logical storage device, to adifferent container that does use the selected access protocol to accessthe logical storage device.

In some embodiments, selecting a particular one of the first and secondaccess protocols for utilization by the logical storage device in agiven one of the monitoring intervals illustratively comprises selectingthe particular one of the first and second access protocols having alowest average response time across its associated paths for at leastone previous one of the monitoring intervals. Again, other types ofperformance measures, or various combinations of multiple suchperformance measures, can be used to inform the selection between accessprotocols as part of the performance-driven application movementdisclosed herein.

In conjunction with movement of the application from a first containerthat uses the first access protocol to a second container that uses thesecond access protocol, or vice versa, at least one of the MPIO drivers112 of at least one of the host devices 102 is configured to temporarilypause sending of IO operations from the application to the logicalstorage device, to allow one or more IO operations previously sent fromthe application to the logical storage device to complete, to instructthe movement of the application between containers, and responsive tocompletion of the application movement between containers, to resumesending of IO operations to the logical storage device.

Additionally or alternatively, some embodiments are illustrativelyconfigured to perform automated seamless migration of a logical storagedevice from one access protocol to another, and vice versa. For example,some automated seamless migration arrangements used hereinillustratively involve storing different versions of one or more hostdevice operating system (OS) data structures in order to facilitate theseamless migration across the multiple access protocols. Thesearrangements illustratively utilize a multi-path layer of one or more ofthe host devices 102 in performing the migration across the multipleaccess protocols, in a manner that ensures that the logical storagedevice appears to a given host device OS as a single logical storagedevice. The multi-path layer in an arrangement of this type can store afirst version of a host OS data structure comprising a first identifierof a logical storage device associated with a first access protocol, andin conjunction with migration of the logical storage device fromutilization of the first access protocol to utilization of a secondaccess protocol different than the first access protocol, to temporarilycontinue to present information from the first version of the OS datastructure in response to one or more requests relating to the logicalstorage device, to obtain a second identifier of the logical storagedevice associated with the second access protocol, to store a secondversion of the host OS data structure comprising the second identifierof the logical storage device associated with the second accessprotocol, and to switch from presenting information from the firstversion of the host OS data structure to presenting information from thesecond version of the host OS data structure. The switch in presentinginformation is illustratively timed to ensure that the logical storagedevice appears to the host OS as the same device both before and afterthe migration from the first access protocol to the second accessprotocol.

In some embodiments, the multi-path layer receives an access protocolchange notification, which initiates the process of automated seamlessmigration of the logical storage device from the first access protocolto the second access protocol. For example, responsive to receipt of theaccess protocol change notification, the multi-path layer isillustratively configured to store the first version of the host OS datastructure comprising the first identifier of the logical storage deviceassociated with the first access protocol.

The access protocol change notification in some embodiments comprises acheck condition notification received from one of the storage arrays 105that includes the logical storage device, and/or at least one commandentered by an administrator or other user via a command line interface(CLI) or other user interface of at least one of the host devices 102.

Additional details regarding other examples of automated seamlessmigration techniques that may be used in illustrative embodiments hereinare disclosed in U.S. patent application Ser. No. 17/106,788, filed Nov.30, 2020 and entitled “Automated Seamless Migration across AccessProtocols for a Logical Storage Device,” and U.S. patent applicationSer. No. 16/797,671, filed Feb. 21, 2020 and entitled “Host Device withEfficient Automated Seamless Migration of Logical Storage Devices acrossMultiple Access Protocols,” each incorporated by reference herein in itsentirety.

Such automated seamless migration techniques are not required, however,and other types of switching between access protocols for one or morelogical storage devices can be used in other embodiments.

It should be noted that references in the above description andelsewhere herein to migration of single logical storage devices acrossmultiple access protocols are non-limiting, and other embodiments cansimultaneously migrate multiple logical storage devices across accessprotocols, through straightforward modification of the techniquesdisclosed herein, as will be readily apparent to those skilled in theart.

Such embodiments advantageously provide enhanced system performance bydynamically switching between SCSI-FC and NVMeF access protocols, andvice versa, or between other arrangements of multiple access protocols,for each of one or more logical storage devices of the system 100. Forexample, some existing HBAs support both multiple access protocols, suchas SCSI-FC and NVMeF modes, so in systems with such HBAs there is noneed to change hardware in order to migrate logical storage devicesbetween the two different access protocols. However, as indicatedpreviously, conventional techniques in these and other contextsgenerally do not permit host devices to dynamically switch a logicalstorage device between multiple access protocols based at least in parton congestion, errors and/or other performance conditions currentlyimpacting one of the access protocols.

The above-described functions associated with performance-drivenmovement of applications of the host device 102-1 are illustrativelycarried out at least in part utilizing the MPIO driver 112-1 and itspath selection logic 114-1. For example, in some embodiments, theperformance-driven application movement functionality can be implementedsubstantially entirely under the control of the MPIO driver 112-1, andin such embodiments the path selection logic 114-1 is illustrativelyconfigured to control performance of one or more steps of the flowdiagram to be described below in conjunction with FIG. 2.

Additional or alternative host device components, such one or morecontainer orchestrators and/or migration control logic implemented inthe host device, can be used to control performance of at least portionsof a performance-driven application movement process such as thatillustrated in FIG. 2.

It is assumed that the other MPIO driver 112-2 is configured in a mannersimilar to that described above and elsewhere herein for the first MPIOdriver 112-1. The MPIO driver 112-2 is therefore similarly configured toselect IO operations from its corresponding one of the sets of IO queues110 for delivery to the storage arrays 105 over the network 104 and toperform at least portions of the disclosed functionality forperformance-driven movement of applications.

Accordingly, aspects of functionality for performance-driven movement ofapplications described above in the context of the first MPIO driver112-1 and the first host device 102-1 are assumed to be similarlyperformed by the other MPIO driver 112-2 and the other host device102-2.

The MPIO drivers 112 may be otherwise configured utilizing well-knownMPIO functionality such as that described in “Dell EMC SC Series Storageand Microsoft Multipath I/O,” Dell EMC, CML1004, July 2018, which isincorporated by reference herein. Such conventional MPIO functionalityis suitably modified in illustrative embodiments disclosed herein tosupport performance-driven application movement.

It is to be appreciated that the above-described features of system 100and other features of other illustrative embodiments are presented byway of example only, and should not be construed as limiting in any way.Accordingly, different numbers, types and arrangements of systemcomponents such as host devices 102, network 104, storage arrays 105,storage devices 106, containers 109, IO queues 110, MPIO drivers 112 andinstances of path selection logic 114 can be used in other embodiments.

It should also be understood that the particular sets of modules andother components implemented in the system 100 as illustrated in FIG. 1are presented by way of example only. In other embodiments, only subsetsof these components, or additional or alternative sets of components,may be used, and such components may exhibit alternative functionalityand configurations. For example, as indicated previously, instances ofmigration control logic implemented in the host devices 102 can be usedto perform at least portions of the functionality for performance-drivenmovement of applications.

The operation of the information processing system 100 will now bedescribed in further detail with reference to the flow diagram of theillustrative embodiment of FIG. 2. The process as shown includes steps200 through 208, and is suitable for use in the system 100 but is moregenerally applicable to other types of systems comprising one or morehost devices and at least one storage system. The one or more hostdevices are illustratively the first and second host devices 102-1 and102-2 of FIG. 1, and the storage system illustratively comprises one orboth of the storage arrays 105, with each such storage array comprisinga plurality of storage devices. The storage devices of each such storagearray are assumed to include logical storage devices such as LUNs orother logical storage volumes.

The steps of the FIG. 2 process are illustratively performed primarilyby or under the control of an MPIO layer comprising one or more MPIOdrivers of respective host devices, such as the MPIO drivers 112-1 and112-2 of the first and second host devices 102-1 and 102-2 of system100, although other arrangements of system components can perform atleast portions of one or more of the steps in other embodiments. Atleast portions of the functionality of the FIG. 2 process may beperformed at least in part in conjunction with a load balancingalgorithm or other type of path selection algorithm executed byinstances of path selection logic 114 of one or more MPIO drivers 112. Agiven host device is referred to as simply a “host” in the FIG. 2process and elsewhere herein.

In step 200, the MPIO layer monitors performance of first and secondsets of paths for accessing a logical storage device of a storage arrayvia respective first and second access protocols. For example, assumeone or more hosts are each configured to access a logical storage deviceusing a first access protocol, illustratively a SCSI access protocol.The FIG. 2 process illustratively involves migration of the logicalstorage device from utilization of the SCSI access protocol toutilization of another access protocol, illustratively an NVMe accessprotocol, and vice versa, based at least in part on results of the pathperformance monitoring, although it is to be appreciated that othertypes of access protocols can be used. The SCSI and NVMe protocolsutilized in the present embodiment are examples of what are moregenerally referred to herein as “first and second access protocols.” TheSCSI and NVMe protocols may more particularly comprise SCSI-FC and NVMeFaccess protocols, respectively, although numerous other types of firstand second access protocols can be used in other embodiments. Thelogical storage device illustratively comprises a LUN or other type oflogical storage volume implemented using storage devices of one or moreof the storage arrays 105.

In step 202, a determination is made as to whether or not at least athreshold amount of performance differential is detected between pathsassociated with the first and second access protocols. For example, thethreshold amount of performance differential may be a specifiedpercentage higher or lower response time in one or more paths associatedwith the first access protocol relative to response time in one or morepaths associated with the second access protocol. Under such a detectedcondition, one of the access protocols has a relatively high performanceand the other access protocol has a relatively low performance. If atleast the threshold amount of performance differential is detected, theprocess moves to step 204, and otherwise returns to step 200 asindicated.

Multiple performance measures may be used in determining whether or notat least a threshold differential exists between paths associated withthe first and second protocols in step 202. For example, different pathsassociated with different access protocols may have similar responsetime measures, but host queue length may exhibit more than a thresholddifferential between the different paths. In such arrangements,determining whether at least a threshold differential exists can includecomparing first performance measures for different paths associated withdifferent access protocols, and if the threshold differential is notdetected using the first performance measures, one or more additionalcomparisons may be sequentially implemented using respective additionalperformance measures, such as host queue length, storage array portcongestion, and many others.

As indicated previously herein, in some embodiments the MPIO layercollaborates with one or more container orchestrators in determiningwhether or not at least a threshold differential exists between pathsassociated with the first and second protocols, or otherwise detectingperformance conditions based at least in part on monitored performance.For example, the MPIO layer and the one or more container orchestratorscan each generate different performance measures as part of theperformance monitoring. This can illustratively involve the one or morecontainer orchestrators generating different performance measures foreach of at least first and second different containers that access thelogical storage device using the respective first and second accessprotocols.

In step 204, the MPIO layer temporarily pauses delivery of IO operationsfrom an application to the logical storage device, and allows anyin-flight IO operations previously sent from the application to thelogical storage device to complete. Although reference is made here andelsewhere to a single application generating IO operations for deliveryto the logical storage device, there may be multiple such applicationseach generating IO operations for delivery to the logical storage devicein other embodiments. Such references to a single application shouldtherefore be viewed as non-limiting examples.

In step 206, the MPIO layer instructs a container orchestrator to movethe application from its current container that uses one of the firstand second access protocols to access the logical storage device to adifferent container that uses the other one of the first and secondaccess protocols to access the logical storage device. For example, theapplication can be moved from one container on a particular host deviceto another container on that same host device, although other types ofapplication movement may be used, such as application movement betweencontainers on different host devices.

It is possible in some embodiments that at least portions of thefunctionality described herein as being separately performed by an MPIOlayer and a container orchestrator can be integrated into a single hostdevice component.

In step 208, after application movement is complete, the MPIO layerresumes delivery of IO operations to the logical storage device.

In some embodiments, live migration of the application from onecontainer to the other container may be performed, such that the pausingand resuming in steps 204 and 208 are not needed.

Additionally or alternatively, some embodiments can implement automatedseamless migration techniques, such as those disclosed in theabove-cited U.S. patent application Ser. Nos. 17/106,788 and 16/797,671.

Again, numerous other types of migration can be used in otherembodiments to migrate a logical storage device from use of one accessprotocol to another, and vice versa.

The steps of the FIG. 2 process are shown in sequential order forclarity and simplicity of illustration only, and certain steps can atleast partially overlap with other steps. Also, one or more of the stepsreferred to as being performed by a particular system component, such asan MPIO layer comprising one or more MPIO drivers, can in otherembodiments be performed at least in part by one or more other systemcomponents.

As indicated above, different instances of the FIG. 2 process canexecute at least in part in parallel with one another for differentlogical storage devices. Also, multiple additional instances of the FIG.2 process can be performed in respective ones of one or more additionalhost devices that share the first and second storage arrays.

The particular processing operations and other system functionalitydescribed in conjunction with the flow diagram of FIG. 2 are presentedby way of illustrative example only, and should not be construed aslimiting the scope of the disclosure in any way. Alternative embodimentscan use other types of processing operations involving host devices,storage systems and functionality for performance-driven movement ofapplications. For example, the ordering of the process steps may bevaried in other embodiments, or certain steps may be performed at leastin part concurrently with one another rather than serially. Also, one ormore of the process steps may be repeated periodically, or multipleinstances of the process can be performed in parallel with one anotherin order to implement a plurality of different performance-drivenapplication movement arrangements within a given information processingsystem.

Functionality such as that described in conjunction with the flowdiagram of FIG. 2 can be implemented at least in part in the form of oneor more software programs stored in memory and executed by a processorof a processing device such as a computer or server. As will bedescribed below, a memory or other storage device having executableprogram code of one or more software programs embodied therein is anexample of what is more generally referred to herein as a“processor-readable storage medium.”

Referring now to FIG. 3, another illustrative embodiment is shown. Inthis embodiment, an information processing system 300 comprises acontainer orchestrator 303, path condition information 311 and pathselection logic 314. Additional components can be included in otherembodiments, such as one or more of host-side migration control logicand storage-side migration control logic, which can perform variousaspects of automated seamless migration in some embodiments herein. Thesystem 300 is configured in accordance with a layered systemarchitecture that illustratively includes a host device processor layer330, an MPIO layer 332, an HBA layer 334, a switch fabric layer 336, astorage array port layer 338 and a storage array processor layer 340. Asillustrated in the figure, the host device processor layer 330, the MPIOlayer 332 and the HBA layer 334 are associated with one or more hostdevices, the switch fabric layer 336 is associated with one or more SANsor other types of networks, and the storage array port layer 338 andstorage array processor layer 340 are associated with one or morestorage arrays (“SAs”).

The system 300 in this embodiment implements performance-drivenapplication movement for each of one or more logical storage volumes orother logical storage devices of one or more storage arrays. The logicalstorage devices store data for one or more application processes runningin one or more host device processors of the host device processor layer330. The functionality for performance-driven movement of applicationsin this embodiment is assumed to be controlled at least in part bycontainer orchestrator 303 of the host device processor layer 330 andpath selection logic 314 of the MPIO layer 332, utilizing path conditioninformation 311, although other arrangements are possible.

The MPIO layer 332 is an example of what is also referred to herein as amulti-path layer, and comprises one or more MPIO drivers implemented inrespective host devices. Each such MPIO driver illustratively comprisesan instance of path selection logic 314 configured to perform pathselection for delivery of IO operations to the storage arrays of system300 as previously described. The path selection logic 314 in someembodiments operates in conjunction with the container orchestrator 303and the path condition information 31 in implementing at least portionsof the functionality for performance-driven application movement asdisclosed herein, such as monitoring path performance and triggeringmovement of applications between containers associated with differentaccess protocols. Additional or alternative layers and path selectionlogic arrangements can be used in other embodiments.

In the system 300, path selection logic 314 is configured to selectdifferent paths for sending IO operations from a given host device to astorage array. These paths as illustrated in the figure include a firstpath from a particular HBA denoted HBA1 through a particular switchfabric denoted SF1 to a particular storage array port denoted PORT1, anda second path from another particular HBA denoted HBA2 through anotherparticular switch fabric denoted SF2 to another particular storage arrayport denoted PORT2.

These two particular paths are shown by way of illustrative exampleonly, and in many practical implementations there will typically be amuch larger number of paths between the one or more host devices and theone or more storage arrays, depending upon the specific systemconfiguration and its deployed numbers of HBAs, switch fabrics andstorage array ports. For example, each host device in the FIG. 3embodiment can illustratively have a set of n paths to a shared storagearray, or alternatively different ones of the host devices can havedifferent numbers and types of paths to the storage array.

The path selection logic 314 of the MPIO layer 332 in this embodimenttherefore selects paths for delivery of IO operations to the one or morestorage arrays having the storage array ports of the storage array portlayer 338.

The MPIO layer 332 also operates in cooperation with containerorchestrator 303 to control the movement of applications betweencontainers associated with different access protocols, in the mannerdescribed elsewhere herein, based at least in part on monitoredperformance as reflected in path condition information 311.

Some implementations of the system 300 can include a relatively largenumber of host devices (e.g., 1000 or more host devices), although asindicated previously different numbers of host devices, and possiblyonly a single host device, may be present in other embodiments. Each ofthe host devices is typically allocated with a sufficient number of HBAsto accommodate predicted performance needs. In some cases, the number ofHBAs per host device is on the order of 4, 8 or 16 HBAs, although othernumbers of HBAs could be allocated to each host device depending uponthe predicted performance needs. A typical storage array may include onthe order of 128 ports, although again other numbers can be used basedon the particular needs of the implementation. The number of hostdevices per storage array port in some cases can be on the order of 10host devices per port. The HBAs of the host devices are assumed to bezoned and masked to the storage array ports in accordance with thepredicted performance needs, including user load predictions.

A given host device of system 300 can be configured to initiate anautomated path discovery process to discover new paths responsive toupdated zoning and masking or other types of storage systemreconfigurations performed by a storage administrator or other user. Forcertain types of host devices, such as host devices using particularoperating systems such as Windows, ESX or Linux, automated pathdiscovery via the MPIO drivers of a multi-path layer is typicallysupported. Other types of host devices using other operating systemssuch as AIX in some implementations do not necessarily support suchautomated path discovery, in which case alternative techniques can beused to discover paths.

Additional illustrative embodiments will now be described. It is assumedin these embodiments that the MPIO driver of a given host deviceprovides the disclosed functionality for performance-driven applicationmovement, utilizing a corresponding instance of path selection logicimplemented in the MPIO driver, possibly with involvement of one or moreother host device components such as container orchestrator 303.

FIG. 4 shows an example of path condition information 400 determined byan MPIO layer of a host device in an illustrative embodiment. The pathcondition information 400 in this embodiment is maintained in the formof a table, although other types of data structures can be used in otherembodiments. Such information is illustratively determined by the MPIOlayer of the host device periodically sending commands over respectivepaths and measuring the corresponding response times. The commands canbe part of one or more IO operations, or separate from the IOoperations. The resulting response time measurements are examples ofwhat are also referred to herein as “latency measures” although othertypes of latency measures, or more generally “performance measures,” canbe used. For example, some embodiments compute average response timesfor each path using multiple commands sent over that path.

In the context of the FIG. 1 embodiment, the path condition information400 is illustratively obtained by a given one of the MPIO drivers 112 ofone of the host devices 102 through interaction with at least one of thestorage arrays 105, and stored by the given MPIO driver in one or moretables or other data structures in at least one memory associated withone or more of the processors of the one or more host devices 102.

In the context of the FIG. 3 embodiment, the path condition information400 corresponds to at least a portion of the path condition information311, and is illustratively obtained by an MPIO layer 332 throughinteraction with the storage array layers 338 and 340, and stored in oneor more tables or other data structures in a memory associated with oneor more of the processors of host device processors layer 330.

The path condition information 400 more particularly comprises aplurality of entries for different ones of the paths to at least onestorage array, with each such entry comprising a path identifier andcurrent condition information for that path. Different ones of the pathsare associated with different ones of first and second containers,denoted as Container 1 and Container 2, respectively, which userespective first and second access protocols, such as respective SCSI-FCand NVMeF access protocols, to access at least one logical storagedevice of at least one storage array.

The paths associated with Container 1 that uses the first accessprotocol are denoted in the figure as Path 1-1, Path 1-2, . . . Path1-J, and have their respective identifiers entered in a first column ofthe table of FIG. 4. Similarly, the paths associated with Container 2that uses the second access protocol are denoted in the figure as Path2-1, Path 2-2, . . . Path 2-K, and also have their respectiveidentifiers entered in the first column of the table of FIG. 4. Thesecond column of the table includes the current condition informationfor the corresponding paths identified in the first column, andillustratively comprises per-path latency measures of the type describedabove. Numerous other types and arrangements of entries and fields canbe used, and the term “path condition information” as used herein istherefore intended to be broadly construed. Such information can bestored in one or more data structures of a multi-path layer of the hostdevice and/or in other data structures elsewhere in the host device. Forexample, different data structures may be used for different paths setsassociated with different access protocols.

Another additional embodiment implements a process that isillustratively performed by an MPIO layer, possibly in cooperation withother host device components, such as one or more containerorchestrators. Such an embodiment can be configured, for example, tomonitor performance of respective ones of a plurality of paths foraccessing at least one logical storage device, and responsive todetection of at least one specified condition in the monitoredperformance relating to at least a subset of the paths, to move at leastone application from a first container that utilizes a first accessprotocol to access the logical storage device to a second container thatutilizes a second access protocol different than the first accessprotocol to access the logical storage device.

The MPIO driver of a given host device in this embodiment is configuredto determine IO processing performance for each of a plurality of pathsby recording IO latency for each path at a desired granularity andmonitoring corresponding IO statistics for each path. For example, IOstatistics such as average response time can be computed and monitoredfor each path using multiple instances of measured response times forthat path. This illustratively involves collecting response time sampleson defined intervals for each path and computing and monitoring thecorresponding IO statistics. An example of such an interval, which isalso referred to herein as a monitoring interval, may be on the order of1 second, although other types and arrangements of monitoring intervalscan be used depending upon the particular needs and othercharacteristics of a given implementation.

Another example of a process for performance-driven application movementimplemented at least in part utilizing an MPIO layer, such as an MPIOlayer comprising MPIO drivers 112 of the FIG. 1 embodiment or MPIO layer332 of the FIG. 3 embodiment, will now be described in more detail.

The process in the present example more particularly comprises analgorithm performed by at least one host device interacting with atleast one storage array, with the one or more host devicesillustratively utilizing their respective MPIO drivers to perform atleast portions of the algorithm.

In this example algorithm, an MPIO driver of multi-pathing software of amulti-path layer of one or more host devices is configured to move atleast one application between containers that use different accessprotocols to access one or more logical storage devices, for example,based on congestion, errors and/or other performance conditionsimpacting a particular one of the storage access protocols. In someembodiments, this involves the MPIO driver monitoring response time orother performance metrics indicative of congestion, errors and/or otherperformance conditions impacting IO operations delivered to a storagearray using a particular one of the access protocols, and responsive todetection of such a condition, instructing the movement of at least oneapplication from a container that uses the particular access protocol toanother container that uses a different access protocol.

It is assumed in this embodiment that the host devices are implementedas respective physical or “bare metal” hosts in a Linux, Windows or AIXenvironment, and are configured to execute respective sets ofcontainers, such as Docker containers or other types of LXCs, under thecontrol of at least one container orchestrator. It is further assumedthat each container runs a separate application and accesses a logicalstorage device of at least one storage array via at least first andsecond access protocols, such as SCSI-FC and NVMeF access protocols. Thelogical storage device is presented by an MPIO driver of a given host todifferent containers of that host as respective pseudo devices.

For example, a Linux host illustratively has two Docker containerswhere:

(a) a first Docker container A uses pseudo device X and communicateswith logical storage device S of a storage array over protocol-1 (e.g.,SCSI-FC); and

(b) a second Docker container B uses pseudo device Y and communicateswith the same logical storage device S of the storage array overprotocol-2 (e.g., NVMeF).

The logical storage device S is masked to the host via two communicationprotocols, and appears to the host OS as two different devices, namelypseudo device X and pseudo device Y. The MPIO driver on the host sendsIOs received from the host OS for pseudo device X to the appropriate HBA(e.g., a protocol-1 HBA) and IOs received from the host OS for pseudodevice Y to the appropriate HBA (e.g., a protocol-2 HBA).

Docker container A illustratively has an application running on it. Thisapplication can be migrated to Docker container B by a Dockerorchestrator, possibly in response to a command sent by the MPIO driverto the Docker orchestrator to move the application from Docker containerA to Docker container B. Such a command can be provided to the Dockerorchestrator via a designated interface, illustratively similar to acommand line interface (CLI), that is made accessible to the MPIOdriver.

In some embodiments, the MPIO driver is primarily implemented in akernel space of the host device, and the Docker orchestrator isprimarily implemented in user space of the host device. The MPIO driverin such embodiments can be configured to include a user-space agent thatallows the kernel-space components of the MPIO driver to interface withthe user-space components of the Docker orchestrator, so as to provideappropriate application movement instructions to the Dockerorchestrator.

The example algorithm for implementing performance-driven applicationmovement includes the following steps:

1. The MPIO driver, possibly operating in cooperation with the Dockerorchestrator, identifies at least one performance issue with protocol-n,where n in accordance with the above illustration involving Dockercontainer A and Docker container B can take on the value 1 or 2, andthus protocol-n can be protocol-1 (e.g., SCSI-FC) or protocol-2 (e.g.,NVMeF), although values of n greater than 2 can used in otherembodiments. Such a performance issue may include, for example, one ofmore of:

(a) Receipt by the MPIO driver of one or more switch notificationsindicating that one or more of the paths of protocol-n are faulty. Theswitch notifications can include, for example, fabric performance impactnotifications (FPINs) received from a switch fabric connecting the hostdevice with the storage array. A given such path is associated with aninitiator on the host (e.g., an HBA of the host) and a target on thestorage array (e.g., a storage array port) and is used to access a givenlogical storage device of the storage array over the switch fabric.

(b) Detection by the MPIO driver of a response time increase forprotocol-n. For example, the MPIO driver can test, for each of aplurality of paths between initiators (e.g., HBAs of the host device)and targets (e.g., storage array ports) for a given logical storagedevice, the response time of each storage access protocol for thatlogical storage device. For example, different sets of pathsillustratively use different access protocols, and one or more suchpaths are tested for each of the access protocols.

(c) Detection by the MPIO driver of suspected slow-drain congestion forprotocol-n.

(d) Detection by the Docker orchestrator of application IO issues forprotocol-n. This is an example of a performance condition that the MPIOdriver may detect in cooperation with the Docker orchestrator. Forexample, the Docker orchestrator can detect the issue, and notify theMPIO driver of the issue, or vice versa.

(e) Other types of issues relating to congestion and/or errors, or otherperformance conditions, can be monitored by the MPIO driver and/or theDocker orchestrator and utilized to identify at least one performanceissue relating to protocol-n.

2. The MPIO driver, responsive to detection of at least one performanceissue with protocol-n in Step 1, swaps access protocols by instructingthe Docker orchestrator to transfer the application from a containerusing protocol-n to a different container using a different one of the nprotocols. For example, in the context of the above illustrationinvolving Docker container A and Docker container B using respectiveprotocol-1 (e.g., SCSI-FC) and protocol-2 (e.g., NVMeF), responsive todetection of at least one performance issue with protocol-1, the MPIOdriver instructs the Docker orchestrator to transfer the applicationfrom Docker container A to Docker container B, such that the applicationwill now utilize protocol-2. Similarly, responsive to subsequentdetection of at least one performance issue with protocol-2, the MPIOdriver instructs the Docker orchestrator to transfer the applicationfrom Docker container B back to Docker container A, such that theapplication will once again utilize protocol-1. The MPIO driver in thepresent example algorithm is assumed to be provided with functionalityto manage reservation transfers if necessary, to drain IO operations onDocker container A before instructing that the application be moved toDocker container B, and vice versa, to manage the two different pseudodevices as one logical storage device, etc.

3. The testing of Step 1 and the protocol swapping of Step 2 areillustratively repeated once every X seconds, or at other suitable timeintervals, in order to dynamically improve the response time performanceof the storage device over time by performance-driven movement ofapplications between containers that use different access protocols toaccess a logical storage device. For example, in some embodiments, thevariable X can take on a value such as 100, 10, 1, 0.1, 0.01, etc. andis illustratively considered a tunable parameter that can be establishedby an administrator or other user.

4. If the average response time measured for an access protocol that isnot currently being utilized to send IO operations to the storage deviceis not lower than that of the currently utilized access protocol by atleast Y %, then the MPIO driver will not swap the protocols. Thisprovides hysteresis to prevent the MPIO driver from swapping betweenaccess protocols too frequently for only limited benefit. The variable Ycan take on a value such as 20%, indicating that a performancedifferential of at least 20% between the access protocols is needed inorder to trigger the swapping of access protocols. Like the variable Xabove, the variable Y can take on other values and is illustrativelyconsidered a tunable parameter.

5. In swapping from a currently utilized access protocol to anotheraccess protocol that exhibits at least the above-noted Y % improvementin average response time, the MPIO driver will pause or “freeze” any newIOs to the logical storage device and drain any existing IOs (e.g.,allow pending IOs to finish). The MPIO driver will then swap to theother access protocol, by instructing the Docker orchestrator to movethe application from Docker container A to Docker container B, andresume or “thaw” new IOs to the storage device.

6. Additional or alternative criteria relating to congestion, errorsand/or other performance conditions can be monitored by the MPIO driverand utilized to control swapping between the access protocols in Steps 1and 2. For example, the protocol swap of Step 2 may occur if at least Z% of the paths to the logical storage device using one or the accessprotocols become non-responsive, “flaky” or exhibit other performanceissues. In some embodiments, the swap of access protocols is triggeredif at least 50% of the paths associated with one of the access protocols(e.g., at least 4 paths in a path set of 8 paths) are experiencingperformance issues. Like the variables X and Y above, the variable Z canalso take on other values and is illustratively considered a tunableparameter.

7. Similar swapping criteria can be monitored based on other types oferrors, as well as switch-reported performance issues, possibly detectedby the MPIO driver and/or the Docker orchestrator using FPINs receivedfrom the switch fabric connecting the host device with the storagearray.

This particular algorithm is presented by way of illustrative exampleonly, and other embodiments can use other types of algorithms to providethe disclosed functionality for seamless migration across storage accessprotocols.

The term “swap” in the context of swapping of access protocols asdisclosed herein illustratively includes an MPIO driver causing acontainer orchestrator to move an application from a first containerthat uses a first storage access protocol to communicate with a storagearray to a second container that uses a second storage access protocolto communicate with the storage array. For physical environments, suchas Linux for example, the term “swap” illustratively includes switchingbetween different path-sets associated with different containers, whereeach path-set uses a different access protocol. It is to be appreciatedthat other types of implementations can be used in other types of hostdevice environments in other embodiments. For example, in an ESXienvironment, the term “swap” illustratively includes vMotion activitybetween different hosts, each using a different access protocol.

Illustrative embodiments herein provide significant advantages overconventional arrangements in which the host OS is configured to operatewith a particular storage access protocol and cannot swap from a currentaccess protocol to another access protocol if the current accessprotocol is experiencing congestion and/or errors, or other types ofperformance issues. For example, bare metal hosts of the type notedabove generally have no ability to fail-over between different storageaccess protocols if necessary.

The MPIO driver portions of the above algorithm may be similarlyperformed by other MPIO drivers on respective other host devices. SuchMPIO drivers illustratively form a multi-path layer comprisingmulti-pathing software of the host devices.

Also, Linux, ESXi and other host environments are used herein asnon-limiting examples only, and the same or similar performance-drivenapplication movement techniques can be used in a wide variety of otherhost device environments. References to Docker containers and Dockerorchestrators above should similarly be viewed as non-limiting examples.

Again, the above algorithm is presented by way of illustrative exampleonly, and other embodiments can utilize additional or alternative steps.Also certain steps illustrated as being performed serially can insteadbe performed at least in part in parallel with one another.

Advantageously, illustrative embodiments can non-disruptively transforma storage access protocol for a logical storage device from SCSI to NVMeand vice versa based at least in part on detected performance conditionscurrently impacting a particular one of the access protocols.

For example, container environments (e.g., with Docker containers orother types of LXCs) are advantageously leveraged in some embodiments tomigrate a logical storage device between different access protocols, forexample, by moving an application from a first container associated witha first storage access protocol to a second container associated with asecond storage access protocol.

Additionally or alternatively, some embodiments provide a storagemulti-pathing driver supporting more than one storage access protocolfor a single managed device.

The particular performance-driven application movement arrangementsdescribed above are presented by way of illustrative example only.Numerous alternative arrangements of these and other features can beused in implementing performance-driven application movement in otherembodiments.

It is apparent from the foregoing that the illustrative embodimentsdisclosed herein can provide a number of significant advantages relativeto conventional arrangements. For example, some embodiments configurehost devices comprising respective MPIO drivers to include functionalityfor performance-driven application movement for logical storage volumesor other types of logical storage devices.

The disclosed functionality can be implemented using a wide variety ofdifferent host devices and storage systems.

It is to be appreciated that the particular advantages described aboveare associated with particular illustrative embodiments and need not bepresent in other embodiments. Also, the particular types of informationprocessing system features and functionality as illustrated in thedrawings and described above are exemplary only, and numerous otherarrangements may be used in other embodiments.

It was noted above that portions of an information processing system asdisclosed herein may be implemented using one or more processingplatforms. Illustrative embodiments of such platforms will now bedescribed in greater detail. These and other processing platforms may beused to implement at least portions of other information processingsystems in other embodiments. A given such processing platform comprisesat least one processing device comprising a processor coupled to amemory.

One illustrative embodiment of a processing platform that may be used toimplement at least a portion of an information processing systemcomprises cloud infrastructure including virtual machines implementedusing a hypervisor that runs on physical infrastructure. The cloudinfrastructure further comprises sets of applications running onrespective ones of the virtual machines under the control of thehypervisor. It is also possible to use multiple hypervisors eachproviding a set of virtual machines using at least one underlyingphysical machine. Different sets of virtual machines provided by one ormore hypervisors may be utilized in configuring multiple instances ofvarious components of the system.

These and other types of cloud infrastructure can be used to providewhat is also referred to herein as a multi-tenant environment. One ormore system components such as virtual machines, or portions thereof,are illustratively implemented for use by tenants of such a multi-tenantenvironment.

Cloud infrastructure as disclosed herein can include cloud-based systemssuch as AWS, GCP and Microsoft Azure. Virtual machines provided in suchsystems can be used to implement a fast tier or other front-end tier ofa multi-tier storage system in illustrative embodiments. A capacity tieror other back-end tier of such a multi-tier storage system can beimplemented using one or more object stores such as Amazon S3, GCP CloudStorage, and Microsoft Azure Blob Storage.

In some embodiments, the cloud infrastructure additionally oralternatively comprises a plurality of containers illustrativelyimplemented using respective operating system kernel control groups ofone or more container host devices. For example, a given container ofcloud infrastructure illustratively comprises a Docker container orother type of LXC implemented using a kernel control group. Thecontainers may run on virtual machines in a multi-tenant environment,although other arrangements are possible. The containers may be utilizedto implement a variety of different types of functionality within thesystem 100. For example, containers can be used to implement respectivecompute nodes or storage nodes of a cloud-based system. Again,containers may be used in combination with other virtualizationinfrastructure such as virtual machines implemented using a hypervisor.

Another illustrative embodiment of a processing platform that may beused to implement at least a portion of an information processing systemcomprises a plurality of processing devices which communicate with oneanother over at least one network. The network may comprise any type ofnetwork, including by way of example a global computer network such asthe Internet, a WAN, a LAN, a satellite network, a telephone or cablenetwork, a cellular network, a wireless network such as a WiFi or WiMAXnetwork, or various portions or combinations of these and other types ofnetworks.

Each processing device of the processing platform comprises a processorcoupled to a memory. The processor may comprise a microprocessor, amicrocontroller, an application-specific integrated circuit (ASIC), afield-programmable gate array (FPGA), a graphics processing unit (GPU)or other type of processing circuitry, as well as portions orcombinations of such circuitry elements. The memory may comprise randomaccess memory (RAM), read-only memory (ROM), flash memory or other typesof memory, in any combination. The memory and other memories disclosedherein should be viewed as illustrative examples of what are moregenerally referred to as “processor-readable storage media” storingexecutable program code of one or more software programs.

Articles of manufacture comprising such processor-readable storage mediaare considered illustrative embodiments. A given such article ofmanufacture may comprise, for example, a storage array, a storage diskor an integrated circuit containing RAM, ROM, flash memory or otherelectronic memory, or any of a wide variety of other types of computerprogram products. The term “article of manufacture” as used hereinshould be understood to exclude transitory, propagating signals.

Also included in the processing device is network interface circuitry,which is used to interface the processing device with the network andother system components, and may comprise conventional transceivers.

As another example, portions of a given processing platform in someembodiments can comprise converged infrastructure such as VxRail™,VxRack™, VxRack™ FLEX, VxBlock™ or Vblock® converged infrastructure fromDell Technologies.

Again, these particular processing platforms are presented by way ofexample only, and other embodiments may include additional oralternative processing platforms, as well as numerous distinctprocessing platforms in any combination, with each such platformcomprising one or more computers, servers, storage devices or otherprocessing devices.

It should therefore be understood that in other embodiments differentarrangements of additional or alternative elements may be used. At leasta subset of these elements may be collectively implemented on a commonprocessing platform, or each such element may be implemented on aseparate processing platform.

Also, numerous other arrangements of computers, servers, storage devicesor other components are possible in an information processing system asdisclosed herein. Such components can communicate with other elements ofthe information processing system over any type of network or othercommunication media.

As indicated previously, components of an information processing systemas disclosed herein can be implemented at least in part in the form ofone or more software programs stored in memory and executed by aprocessor of a processing device. For example, at least portions of thefunctionality of host devices 102, network 104 and storage arrays 105are illustratively implemented in the form of software running on one ormore processing devices. As a more particular example, the instances ofpath selection logic 114 may be implemented at least in part insoftware, as indicated previously herein.

It should again be emphasized that the above-described embodiments arepresented for purposes of illustration only. Many variations and otheralternative embodiments may be used. For example, the disclosedtechniques are applicable to a wide variety of other types ofinformation processing systems, utilizing other arrangements of hostdevices, networks, storage systems, storage arrays, storage devices,processors, memories, containers, IO queues, MPIO drivers, pathselection logic, migration control logic and additional or alternativecomponents. Also, the particular configurations of system and deviceelements and associated processing operations illustratively shown inthe drawings can be varied in other embodiments. For example, a widevariety of different host device, MPIO driver and storage systemconfigurations and associated performance-driven application movementarrangements can be used in other embodiments. Moreover, the variousassumptions made above in the course of describing the illustrativeembodiments should also be viewed as exemplary rather than asrequirements or limitations. Numerous other alternative embodimentswithin the scope of the appended claims will be readily apparent tothose skilled in the art.

1. An apparatus comprising: at least one processing device comprising aprocessor coupled to a memory; said at least one processing device beingconfigured: to monitor performance of respective ones of a plurality ofpaths for accessing a logical storage device; and responsive todetection of at least one specified condition in the monitoredperformance relating to at least a subset of the paths, to move at leastone application from a first container that utilizes a first accessprotocol to access the logical storage device to a second container thatutilizes a second access protocol different than the first accessprotocol to access the logical storage device; wherein said at least oneprocessing device comprises at least a portion of at least one hostdevice coupled to a storage system via at least one network.
 2. Theapparatus of claim 1 wherein the first access protocol comprises a SmallComputer System Interface (SCSI) access protocol and the second accessprotocol comprises a Non-Volatile Memory Express (NVMe) access protocol3. The apparatus of claim 2 wherein the SCSI access protocol comprises aSCSI over Fibre Channel (SCSI-FC) access protocol and the NVMe accessprotocol comprises an NVMe over Fabrics (NVMeF) access protocol. 4.(canceled)
 5. The apparatus of claim 1 wherein the paths are associatedwith respective initiator-target pairs and wherein each of a pluralityof initiators of the initiator-target pairs comprises a correspondinghost bus adaptor of said at least one host device and each of aplurality of targets of the initiator-target pairs comprises acorresponding port of the storage system.
 6. The apparatus of claim 1wherein said at least one host device comprises a multi-path layer, themulti-path layer comprising at least one multi-path input-output driverconfigured to control delivery of input-output operations from said atleast one host device to the storage system over selected paths throughthe network.
 7. The apparatus of claim 1 wherein monitoring performanceof respective ones of a plurality of paths for accessing a logicalstorage device comprises: monitoring performance of a first set of pathsassociated with the first access protocol; and monitoring performance ofa second set of paths associated with the second access protocol.
 8. Theapparatus of claim 7 wherein monitoring performance of the first andsecond sets of paths associated with the respective first and secondaccess protocols is performed at least in part by a multi-path layer ofthe at least one host device.
 9. The apparatus of claim 7 whereinmonitoring performance of the first and second sets of paths associatedwith the respective first and second access protocols is performed atleast in part by a container orchestrator of the at least one hostdevice.
 10. The apparatus of claim 6 wherein the multi-path layer of theat least one host device presents the logical storage device to thefirst and second containers as respective first and second distinctpseudo devices.
 11. The apparatus of claim 10 wherein an operatingsystem of the at least one host device sees the logical storage deviceas the first and second distinct pseudo devices.
 12. The apparatus ofclaim 10 wherein the multi-path layer of the at least one host devicedirects input-output operations received from the first container forthe first pseudo device to a first host bus adaptor associated with thefirst access protocol and directs input-output operations received fromthe second container for the second pseudo device to a second host busadaptor associated with the second access protocol.
 13. The apparatus ofclaim 6 wherein the multi-path layer of the at least one host device,responsive to detection of the at least one specified condition,instructs a container orchestrator of the at least one host device tomove the at least one application from the first container that utilizesthe first access protocol to access the logical storage device to thesecond container that utilizes the second access protocol to access thelogical storage device.
 14. The apparatus of claim 6 wherein themulti-path layer of the at least one host device comprises one or morekernel-space components implemented in a kernel space of the at leastone host device and one or more user-space components implemented in auser space of the at least one host device, and wherein the one or moreuser-space components of the multi-path layer comprise a user agentconfigured to provide an interface between at least a subset of the oneor more kernel-space components of the multi-path layer and at least oneuser-space component of a container orchestrator of the at least onehost device.
 15. A computer program product comprising a non-transitoryprocessor-readable storage medium having stored therein program code ofone or more software programs, wherein the program code, when executedby at least one processing device comprising a processor coupled to amemory and configured to communicate over at least one network with astorage system, causes said at least one processing device: to monitorperformance of respective ones of a plurality of paths for accessing alogical storage device; and responsive to detection of at least onespecified condition in the monitored performance relating to at least asubset of the paths, to move at least one application from a firstcontainer that utilizes a first access protocol to access the logicalstorage device to a second container that utilizes a second accessprotocol different than the first access protocol to access the logicalstorage device; wherein said at least one processing device comprises atleast a portion of at least one host device coupled to the storagesystem via the at least one network.
 16. The computer program product ofclaim 15 wherein a multi-path layer of the at least one host devicepresents the logical storage device to the first and second containersas respective first and second distinct pseudo devices.
 17. The computerprogram product of claim 15 wherein a multi-path layer of the at leastone host device, responsive to detection of the at least one specifiedcondition, instructs a container orchestrator of the at least one hostdevice to move the at least one application from the first containerthat utilizes the first access protocol to access the logical storagedevice to the second container that utilizes the second access protocolto access the logical storage device.
 18. A method comprising:monitoring performance of respective ones of a plurality of paths foraccessing a logical storage device; and responsive to detection of atleast one specified condition in the monitored performance relating toat least a subset of the paths, moving at least one application from afirst container that utilizes a first access protocol to access thelogical storage device to a second container that utilizes a secondaccess protocol different than the first access protocol to access thelogical storage device; wherein the method is performed by at least oneprocessing device comprising a processor coupled to a memory; andwherein said at least one processing device comprises at least a portionof at least one host device coupled to a storage system via at least onenetwork.
 19. The method of claim 18 wherein a multi-path layer of the atleast one host device presents the logical storage device to the firstand second containers as respective first and second distinct pseudodevices.
 20. The method of claim 18 wherein a multi-path layer of the atleast one host device, responsive to detection of the at least onespecified condition, instructs a container orchestrator of the at leastone host device to move the at least one application from the firstcontainer that utilizes the first access protocol to access the logicalstorage device to the second container that utilizes the second accessprotocol to access the logical storage device.
 21. The method of claim18 wherein monitoring performance of respective ones of a plurality ofpaths for accessing a logical storage device comprises: monitoringperformance of a first set of paths associated with the first accessprotocol; and monitoring performance of a second set of paths associatedwith the second access protocol.